Do not allow the subject to be distant
Get the horizon straight
Beware of your reflection
Never use inexpensive film
&
Check you have not got anything growing from the subjects face
Fill the camera frame
Train yourself to look at everything that will appear in the finished image
Centre your subjects
Find a good photographic laboratory
Never photograph in strong wind
Amateur Photography in London by Tim Walker. Vogue Italia 10/98. Mostly via W&S&H